Optimizing in vitro mineral nutrition and plant density increases greenhouse growth of Curcuma longa L. during acclimatization
2016
El-Hawaz, Rabia | Park, Dara | Bridges, William C. | Adelberg, Jeffrey
The growth of plantlets during hardening is affected by the tissue culture media in which they were grown. A multi-factor approach to optimizing nutrient ions in media for subsequent ex vitro growth has not been studied. A response surface method was designed to test in vitro plant density (50–250 buds/L), [Formula: see text] (6.25–10.25 mM), Ca²⁺ (2–10 mM), and KNO₃ (18–100 mM) in low [Formula: see text] on medium as it affected subsequent growth in a 21 days acclimatization period with Curcuma longa genotypes (L35-1 and L22-5). The treatment media were compared with the MS medium. Plants grown on treatment media had higher relative fresh biomass (3.3 ± 0.5 fold from high-density with 42 mM KNO₃; 3.7 ± 0.5 fold from low-density with 18 mM KNO₃) than MS plants (2.6 ± 0.5 fold) regardless of plant density. Leaf area index from the treatments (67.0 ± 16.4 cm²/bud from high-density with 70.4 mM KNO₃; 78.4 ± 16.4 cm²/bud from low-density with 50.7 mM KNO₃) was higher than MS plants (22.0 ± 8 cm²/bud from high-density and 36.0 ± 8 cm²/bud from low-density). Shoots from treatment plants receiving 64 mM KNO₃, elongated to 8.6 ± 0.9 cm from high-density and 10.9 ± 0.9 cm from low-density. Genotype L22-5 elongated to 6.0 ± 0.6 cm regardless of density, and L35-1 elongated to 6.0 ± 0.6 cm from low-density and to 4.0 ± 0.6 cm from high-density. Raising phosphate 5× to 10× the MS concentration in the pre-hardening media did not influence ex vitro responses. Plants grown on modified low ammonium media can grow faster and larger during acclimatization with increased KNO₃, especially from high-density culture that would be preferred in commercial applications.
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